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Ultraviolet observations of the central star in the planetary nebula 136+5 1.
Heckathorn, J. N.; Fesen, R. A.
Ultraviolet spectra obtained with IUE are presented which confirm the Heckathorn et al. (1982) stellar candidate as the central star of the recently discovered planetary nebula 136+5°1. Spectra of the star covering the 1200 - 2000 Å range show a featureless continuum indicative of a black body temperature between 50,000 and 60,000K. Anomalously lo…
Chromospherically active stars. I. HD 136905.
Fekel, F. C.; Africano, J. L.; Quigley, R. +3 more
The variable star HD 136905, recently designated GX Librae, is a chromospherically active K1 III single-lined spectroscopic binary with a period of 11.1345 days. It has moderate strength Ca II H and K and ultraviolet emission features, while Hα is strongly in absorption. The inclination of the systems is 58°±17° and the unseen secondary is most li…
Interstellar reddeningh law towards the nucleus of H Per.
Franco, M. L.; Stalio, R.; Magazzu, A.
The extinction curves in the direction of four early-B main-sequence stars located in the nucleus of h Per (BD + 56 deg 501, BD + 56 deg 510, BD + 56 deg 516 and BD + 56 deg 517) and compared to one another and to the extinction curves derived from eight stars located in the same general area but lying at different distances. Data from UBV photome…
IUE high-resolution observations of Mira B.
Reimers, D.; Stickland, D. J.; Cassatella, A. +2 more
A high-resolution spectrum of Mira obtained with IUE on 1983 July 7 confirms the presence of broad emission lines with typical half base widths of ≅300 to roughly 1000 km s-1. No narrow emission lines are detected. The observed broad lines cannot originate from the extended atmosphere of the cool giant variable. The authors show in part…
Outflow in the nucleus of the Seyfert I galaxy NGC 3783.
Wamsteker, W.; Barr, P.
Averaged low-resolution IUE spectra of the Seyfert I galaxy NGC 3783 at two brightness levels are presented. The wavelength interval 1250-1400 A, which is essentially free of emission lines in active galaxies, contains two absorption lines at 1303 A and 1335 A. The line at 1303 A shows, in contrast to the line at 1335 A, considerable variations wi…
IUE spectroscopy, visible-band photometry and polarimetry of HD 47732(V641 Monocerotis).
Koch, R. H.; Hrivnak, B. J.; Bradstreeet, D. H. +3 more
Several high- and low-dispersion IUE spectra are described for the hot, massive close binary HD 47732. The stellar silicon lines do not show theoretically expected strength, the weakness being attributed to incipicent emission. A weak stellar wind is measurable with an expansion velocity of about 500 km/s. There is difficulty in fitting a model at…
On the planetary nebula NGC 3918.
Pena, M.; Torres-Peimbert, S.
We have obtained for this nebula high dispersion lUE spectra in the short and long wavelength ranges and with different exposure times. We have measured the emission line intensities and analyzed them. The density derived fiom different ions confirm that the nebula has no systematic density variations. The collisionally excited lines of [Mg V] 278…
Coordinated optical-EXOSAT-tenma observations of a burst from 2S1636-536
van Paradijs, J.; Pedersen, H.; Lewin, W. H. G. +6 more
During a coordinated observations of 2S1636-536 with EXOSAT, Tenma and the 1.4 metre Danish telescope at La Silla, a single burst was detected at all three observatories. The burst was bright with a peak flux of 6 × 10-8 ergs/cm 2 /s and rapid expansion of the blackbody radius. EXOSAT and Tenma agree closely in the values of…
Time-resolved UV spectroscopy of BE Ursae Majoris.
Hutchings, J. B.; Cowley, A. P.
Far-ultraviolet spectra have been obtained of the eclipsing, hot subdwarf binary, BE UMa, with phase coverage in the 2.3-day orbital period concentrated near minimum light. No clearly phase-related spectral changes were found, but the UV continuum appeared to be in a highly variable state, with changes of a factor of two occurring on a time scale …
The X-Ray and Optical Variability of the BLRG 3C390.3
Ward, M.; Barr, P.; Shafer, R.
We describe the optical emission line and continuum changes in 3C390.3. Also we present new EXOSAT results, and discuss their implication for determination of the X-ray spectrum — spectral index and absorbing column.